Figure (X) is a square with one part missing. Select the piece that fills the missing part exactly. (The piece may be turned round, but not resized.)

Answer & explanation
Correct answer: option 4
The correct answer is Option (4) →

The missing part of the 4 × 4 square in Figure (X) covers 4 small squares. The piece that fits must have exactly this shape and size. The piece in Option (4) fills the gap exactly.

Option (1) — Incorrect. This piece has one small square more than the gap, so it cannot fit into it.
Option (2) — Incorrect. This piece has one small square less than the gap, so a space would be left in the square.
Option (3) — Incorrect. This piece covers as many small squares as the gap, but one of them is in a different place, so it does not fit the gap even when turned round.